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@PHDTHESIS{Frank:874599,
      author       = {Frank, Matthias},
      title        = {{R}eversible wasserstoffbetriebene {F}estoxidzellensysteme},
      volume       = {475},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2020-01527},
      isbn         = {978-3-95806-430-0},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {187},
      year         = {2019},
      note         = {Dissertation, RWTH Aachen University, 2019},
      abstract     = {Renewable energy sources such as wind and solar energy
                      shall cover a large part of theelectricity demand in the
                      future. However, the natural fluctuation of these energy
                      sources leadsto a fluctuating electricity production, which
                      is not always in accordance with demand. Thestorage of
                      surplus electricity and the delayed reconversion in case of
                      electricity demandrepresents a solution to counteracting
                      this issue. Due to the large amount of energy, a
                      chemicalstorage is particularly suitable for this purpose.
                      To realize this solution, conversion of electricalinto
                      chemical energy with solid oxide cells by steam electrolysis
                      can takes place first. Theproduced hydrogen is temporarily
                      stored and will be reconverted at electricity demand with
                      thesame solid oxide cells by fuel cell operation. This
                      offers an economic advantage over systemswith two solid
                      oxide cell stacks. Due to the pure hydrogen/steam operation,
                      this reversible solidoxide cell system (rSOC-system) is
                      environmentally friendly and thereby differs from the
                      knownrSOC-systems which are using carbonaceous energy
                      sources.The main objective of this work is the research of a
                      technically and economically efficienthydrogen-powered
                      rSOC-system. First, the developments of the system design
                      and of theoperating strategies, which should ensure a safe
                      and fast operating point change, have priority.In order to
                      develop a highly efficient rSOC-system, the system
                      components were investigatedexperimentally. Based on this,
                      dynamic component models were created, which were
                      validatedwith the help of the examination results. The
                      ensuing system models are basing on theinterconnection of
                      the validated component models and allow investigations at
                      system level.The final economic analysis represents the
                      economic viability of the investigatedrSOC-systems. This
                      analysis takes different quantities, system sizes and system
                      designs intoaccount. The influence of varying electricity
                      generation costs and operating hours is shown ina
                      sensitivity analysis.First, an rSOC basic system was
                      developed that only contains necessary components
                      foroperation. This system achieved an efficiency of $43.4\%$
                      and is the starting point for theinvestigation of efficiency
                      enhancing-measures. On the one hand, the efficiency could
                      beincreased to $45.5\%$ via an internal heat recovery in
                      electrolysis operation and, on the otherhand, the parasitic
                      system consumption could be significantly reduced with the
                      integration ofan off-gas recirculation. In addition, a
                      condenser is included in the recirculation which
                      mainlyenables the recirculation of hydrogen and leads to an
                      efficiency increase to $49.9\%.$ Theoperating strategies
                      developed for this final rSOC-system enables, inter alia, a
                      system startupin two hours. The load change from full load
                      to $50\%$ partial load takes ten minutes in fuel
                      celloperation and three minutes in electrolysis operation.
                      Switching between these two operatingmodes is possible in
                      less than five minutes. For the solid oxide cells critical
                      operating areaswere analyzed and avoided. The economic
                      analysis showed that a 5 kW rSOC-system can beeconomical
                      from 100 units upwards in comparison to mains supply. This
                      system pays for itselfafter only seven years, resulting in
                      electricity generation costs of € 0.232 / kWh (100 units)
                      upto € 0.148 / kWh (100,000 units). rSOC-systems with
                      higher power output (≥ 50 kW) pay forthemselves later and
                      at higher quantities because the competing electricity price
                      by mainssupply decreases with increasing purchase
                      quantities.},
      cin          = {IEK-3 / IEK-14},
      cid          = {I:(DE-Juel1)IEK-3-20101013 / I:(DE-Juel1)IEK-14-20191129},
      pnm          = {135 - Fuel Cells (POF3-135) / SOFC - Solid Oxide Fuel Cell
                      (SOFC-20140602)},
      pid          = {G:(DE-HGF)POF3-135 / G:(DE-Juel1)SOFC-20140602},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2020060532},
      url          = {https://juser.fz-juelich.de/record/874599},
}